Interventional Exclusion of Iliac Artery Aneurysms Using the Flow-Diverting Multilayer Stent

A systematic review and meta-analysis of the performance of flow-diverting stents in the treatment of peripheral and visceral artery aneurysms

OBJECTIVE

This meta-analysis aims to evaluate the safety and efficacy of flow-diverting stents (FDS) in treating peripheral and visceral artery aneurysms (PAA/VAAs).

BACKGROUND

Though rare, PAA/VAAs can represent a life-threatening condition due to their propensity of rupture. The FDS emerges as a new solution to exclude these aneurysms while maintaining collateral branches, but convincing evidence is lacking on its clinical effectiveness.

METHODS

A systematic literature search was performed to identify studies related to FDS in treating PAA/VAAs. The preferred reporting items for systematic reviews and meta-analyses (PRISMA) statement was applied to guide the data extraction, quality assessment, and synthesis of outcomes of interest. Random effect models were applied to calculate the event rates of major endpoints. OpenMeta[Analyst] software was used for statistical analysis.

RESULTS

Of 130 records screened, 10 cohort studies (including 220 patients, average age: 66.0 years, 78.4% male) were enrolled in the meta-analysis. Pooled data suggested a technical success rate of 98.5% (95% CI: 97.0-100%). During a mean follow-up period of 14.1 months, 93.6% (95% CI: 88.6-98.5%) side branches remained patent, 89.8% (95% CI: 84.3-95.3%) aneurysms were totally thrombosed, whereas shrinkage/stabilization of the aneurysm was documented in 93.4% (95% CI: 88.4-98.4%) cases. The primary stent patency rate was estimated to be 87.9% (95% CI: 81.0-94.8%). Overall clinical success was achieved in 83.2% (95% CI: 74.4-92.0%) patients.

CONCLUSIONS

The FDS features a potential advantage of preserving side branches while inducing sac thrombosis and aneurysm shrinkage/stabilization. Further prospective, comparative studies in larger patient cohorts are anticipated to draw a robust conclusion.

A Study on the Pressure-Lowering Effect of the Multilayer Stent

BACKGROUND

The objective of the study was to investigate the hemodynamic changes of the blood flow in the aneurysm model after the multilayer stent placement using the fluid dynamic method, to analyze the effectiveness and properties of the multilayer stent in the treatment of aortic aneurysms.

METHODS

A water tank was filled with 5 L of experimental liquid after the circular flow pressure test platform with a glass aneurysm model, and a multilayer stent was built. Pressure at the middle part and the distal aneurysm neck part of the model was then measured. At each site, the pressure was measured 20 times at 1-min intervals, and the testing results were averaged for accuracy.

RESULTS

Without the stent, mean pressure at the middle part and at the distal aneurysm neck part of the model was 11.19 ± 0.23 Kpa and 13.31 ± 0.28 Kpa, respectively. With the stent, the mean pressure decreased to 10.60 ± 0.27 Kpa and 12.60 ± 0.29 Kpa, and the average difference was 0.59 ± 0.15 Kpa and 0.71 ± 0.15 Kpa, respectively.

CONCLUSIONS

After the placement of the multilayer stent, pressure inside the model at the middle part and distal neck part could both be diminished, yet the mean dropped pressure may be too small to be sufficient to cause significant impact on preventing the expansion of abdominal aortic aneurysm; therefore, the pressure-lowering effect of the multilayer stent for abdominal aortic aneurysm may not be ideal compared with the traditional covered stents.

Endovascular management of iliac aneurysmal disease with hypogastric artery preservation

Common iliac artery aneurysms (CIAAs) pose a challenge in endovascular aneurysm repair. Aneurysm repair of CIAA traditionally requires embolization of the ipsilateral hypogastric artery (HA). Symptoms of buttock claudication and more feared complications of pelvic ischemia make HA preservation an appealing addition to aneurysm repair. In this review, we discuss various methods of CIAA repair with devices specifically designed for aneurysm repair and other custom techniques of HA preservation.

Hemodynamics study of a multilayer stent for the treatment of aneurysms

Background

The changes of hemodynamics caused by the implantation of multilayer stent (MS) have significant effects for aneurysm sac.

Methods

Comparisons of 3D numerical models with/without a MS in an abdominal aortic aneurysm with a 90° branch vessel were numerically studied from the viewpoint of hemodynamics.

Results

The results showed that: (1) The flow fields and Wall Shear Stress (WSS) are changed dramatically after MS implantation. The velocity of the blood flow in aneurysm sac decreases significantly and the regions of low-WSS increase. These help thrombus formation; (2) The pressure in aneurysm slightly decreases and keeps close to the normal level of blood pressure, however the risk of aneurysm enlargement or even rupture still exists; (3) The flux and the velocity in branch artery are reduced by about half after MS implantation. Due to the implantation of MS, the changes in the flow field causes the decrease of pressure/WSS in aneurysm sac and the blood flow in branch vessel.

Conclusions

The implantation of MS into abdominal artery results in more low-WSS regions inside aneurysm which induces thrombus formation. The pressure is reduced slightly means the risk of aneurysm rupture exists.

Endovascular Repair of Blunt Popliteal Arterial Injuries

OBJECTIVE

To evaluate the feasibility and effectiveness of endovascular repair for blunt popliteal arterial injuries.

MATERIALS AND METHODS

A retrospective analysis of seven patients with clinical suspicion of popliteal arterial injuries that were confirmed by arteriography was performed from September 2009 to July 2014. Clinical data included demographics, mechanism of injury, type of injury, location of injury, concomitant injuries, time of endovascular procedures, time interval from trauma to blood flow restoration, instrument utilized, and follow-up. All patients were male (mean age of 35.9 ± 10.3 years). The type of lesion involved intimal injury (n = 1), partial transection (n = 2), complete transection (n = 2), arteriovenous fistula (n = 1), and pseudoaneurysm (n = 1). All patients underwent endovascular repair of blunt popliteal arterial injuries.

RESULTS

Technical success rate was 100%. Intimal injury was treated with a bare-metal stent. Pseudoaneurysm and popliteal artery transections were treated with bare-metal stents. Arteriovenous fistula was treated with bare-metal stent and coils. No perioperative death and procedure-related complication occurred. The average follow-up was 20.9 ± 2.3 months (range 18-24 months). One patient underwent intra-arterial thrombolysis due to stent thrombosis at 18 months after the procedure. All limbs were salvaged. Stent migration, deformation, or fracture was not found during the follow-up.

CONCLUSION

Endovascular repair seems to be a viable approach for patients with blunt popliteal arterial injuries, especially on an emergency basis. Endovascular repair may be effective in the short-term. Further studies are required to evaluate the long-term efficacy of endovascular repair.

Severe visceral ischemia and death after multilayer stent deployment for the treatment of a thoracoabdominal aortic aneurysm

The treatment of thoracoabdominal aortic aneurysms, both surgical and endovascular, has always been challenging. In the last years, the multilayer stent has emerged as an alternative device for the treatment of this condition. In this paper, we describe a catastrophic complication of the multilayer stent in a patient with thoracoabdominal aortic aneurysm, a case of massive visceral ischemia and death 3 months after stent deployment.